I made a DIY "linear ram pump" from a design I saw on YouTube, and made some changes so the internal parts would be more serviceable, and replaced with tractor tire rim liners used as the rubber check valve and ejector valve hinge/ seal.
Tested it completely submerged, and doesn't make a sound.
I only tested the pump under simulated conditions, never had a chance to install it in a river as I was planning. I was short on intake line length by about 100 feet to have the intake above the rapids and pump setup at the bottom, to hopefully achieve enough difference in hight for the ram pump to work.
Sorry I broke my phone with photos and videos on it, so here's a link to my Instagram story highlight if anyone is interested to see it in action. The pump in the video isn't the completed version, I have schedule 40 pipe for the final version, but I wanted to test it before committing to permanently glueing approx. $400 CAD of pipe and fittings together. Granted some of that cost was for threaded reducers, so I could experiment with intake line diameters. I settled on 1.25 inch cause I had about 220 feet of it laying around. The person who came up with the original design suggests the use of schedule 40 pipe up to 4inch diameter, larger diameter than that he suggests metal pipe.
I never thought about condensation forming inside the heater when the tote of water cools back down. I wonder if that will really be something to worry about, or maybe when the mass of water is cooling down, the heater will be cooling down at the same rate and won't condensate. I'm really not sure.
And with regards to mounting the heater under the tote, in order to achieve that I would need to be considerably more confident in the gasket for any leaks. It would also mean I need to fabricate a stand for the tote to sit on, and full they weigh 2500# I believe.
I'd really like the whole thing to be as self contained as possible. And empty tote is fairly easy to move, and isn't going to tip over even if the ground is slightly off level.
I'm also off grid, I don't have the ability to add circulating pumps to any type of coil, and I also want to stay away from a coil or external piping which could freeze between fires. For me the whole point of this is to warm the water up, and then be able to let it sit for a few days to a week without having to worry about it freezing.
I'm not opposed to venting the exhaust out the side of the tote, I could go through the same flange for the feed tube, and I would be able to play around with different configurations.
Would insulating the exhaust perhaps help add some draw to the system? rather than having it exit under the same cold water.
I'm not personally opposed to using external fuel to help tings get heated up, a splash of used motor oil, bad diesel fuel?
If worst comes to worst, I seal up the flange hole, I've got an open tank, and I can maybe the heater would work better freestanding in air. And I'm not out a while lot of money, and it will be a fun experiment.
Okay I don't mind the idea of having a J tube heater outside of the tote, and I could flange the exhaust flue into the tote, around the base, and then out another flange.
That's just a lot of fabricating and material to do so.
I would also like the unit as a whole to be somewhat portable, so building a larger, heavier rocket heater on the ground and pumping heat into it isn't my top choice.
So back to theorizing having a submerged rocket mass heater... If I had a taller tank to accommodate a larger heat riser to stay within the suggested ratios, managed to insulate the riser within the tank, maybe then the riser would be able to stay warm enough for proper combustion?
Thanks for the reply and welcoming to the forum Eliot.
I've got a few questions, and some answers to what I'm thinking.
What is a "5 minute riser"?
What are your concerns about submerging the bell?
I would plan to make a gasket as you say, and bolt the flange up to the tank, I was leaning that way to be able to remove it if need be, and wasn't aware about the difficulty of having something like an RTV gasket stick to the tote.
And I was visualizing the top handle of the tank to rest on the bottom of the tote or perhaps a concrete paving stone with anchors to prevent it from floating, as well as being held in place by the flange. That should hopefully give it more than enough of a barrier with the water surrounding it.
I'll try and look at a way to insulate the riser/ form it so the metal could wear away leaving only the riser. Would a heat clay be able to be packed in and hold its form if the internal pipe wastes away? My concern is using a 4 inch pipe as the inside, going up to something like a 6 inch for the outside will not only be much harder to source, but also leave very little room inside the tank after that.
I also would like stay within the size of a 20# tank because of the small space of the tote, I'd like the unit to be able to rest under a bench. So hopefully that size allows for a proper height riser in relation to the feed tube.
And I think having the heater inside a vessel will solve the problems in point 4 and 5 from Eliots response in the thread above.
The bell as he calls it will be completely submerged, and the riser won't be in contact with water, but surrounded by hot exhaust gases before venting out the chimney from somewhere around the base, similar to the photo I attached from another build thread.
This is the type of design I'd like to try, except an angled feed tube that meets up with the riser inside the tank, instead of vertical and horizontal. And also house it all within a 20# tank.
Okay guys, I'll start with a quick introduction, I've been interested in rocket stoves/ rocket mass heaters for a number of years, and google yields a lot of results from this site, so I figured it's time to join and ask the experts for some input prior to attempting my first heater.
I part time off grid, I've build a wood barrel sauna next to the river, and next I'd like to add a plunge tank. I've got a couple IBC totes I received for free and I'm willing to cut one up to make a plunge tank.
My issues being off grid, is keeping it from freezing.
Design: what I'm thinking is build a self feeding rocket heater housed within a propane tank or similar metal vessel, but really, it will be whatever is cheap and available, so I'm leaning towards that. Of course I'll take all necessary precautions prior to cutting or welding.
I know it's mentioned that metal for the burn chamber is subject to extreme temperature will burn through eventually and isn't ideal, and should properly be insulated by fire brick or clay. Unfortunately I don't think that will be possible inside a propane tank due to its size. So perhaps adding metal plates surrounding the burn chamber might buy it some time? It also won't be running daily, the intentions are only to keep the IBC tote from freezing, so maybe weekly burns, or maybe the odd extended burn to get he water up to hot tub temperature, if it's even possible. Again, primary goal is to keep the water from freezing, and it would be a bonus if I could get it to hit tub temperatures!
I would like to have the burn chamber and riser within the propane tank, and the heat pass around the outside of the riser and exhaust out a chimney from the side of the bottom of the tank.
So up until this point this heater would work above water, what I'm proposing is to have the angled feed tube extend through the side of the IBC tote by means of a gasketed metal flange bolted in place that surrounds the feed tube as well as ash clean out/ air feed. Hopefully the water in contact with the metal "flange" coupled with some distance until the plastic tote would prevent it from ever melting. And of course have the chimney from the unit extend above the water line.
What in hoping this would accomplish by having the top of the heat riser submerged, with a jacket around it before passing exhaust is to extract the maximum amount of heat from the fire while also keeping the burn chamber and heat riser hot (as opposed to the water pulling heat directly from an unjacketed heater such as a commercialy available hot tub snorkel stove).
By means of the gasket and bolts, the entire heater could be removed from a drained tank come time when the burn chamber burns through, or should a weld spring a leak and flood the entire system and require re welding.
This design would also allow the heater to be positioned at the bottom of the IBC tote and housed under a wooden bench, heating cooler water and theoretically allowing for more volume of water above the heater to be warmed up, addressing an issue I've found with my parents snorkel stove hot tub.
